1. Field of the Invention
The invention is an actuator used to move and hold ergonomic supports for seats and chairs.
2. Related Art
Automobile and furniture seats frequently include ergonomic supports, such as lumbar supports. There are several types of lumbar supports, including arching pressure surfaces, See, e.g. U.S. Pat. No. 5,397,164, push paddle type lumbar supports, See, e.g. U.S. Pat. No. 4,295,681, and strap type supports, See, e.g. U.S. patent application Ser. No. 09/485,738. The common features shared by all these varieties of ergonomic support include being continuously positionable and being operated by an actuator installed on an exterior surface of the seat so that it can be controlled by person sitting in the seat. Many of these actuators are manual, mechanical devices.
Continuously positionable ergonomic supports have a range of motion. The support device can be moved through its range of motion by the actuator in continuous, stepless fashion. The actuators for these supports include a variety of clutches or brakes so that any position in the range of motion that the user finds comfortable may be held in place by the actuator.
The actuators move and hold the ergonomic supports by means of traction cables in the majority of cases. The most common traction cable is a Bowden cable. A Bowden cable is a flexible conduit or sleeve. A wire is disposed inside the sleeve and is axially slideable through it. At one end of the Bowden cable, the sleeve end is mounted on one part of the ergonomic support and the wire end is mounted on another part of the ergonomic support. Traction drawing the wire through the sleeve moves the ergonomic support and the release of tension on the Bowden cable wire allows the ergonomic support to return through the same range of motion in reverse.
At the other end of the Bowden cable, an actuator must be able to pull the Bowden cable wire through the Bowden cable sleeve in order to move the ergonomic support through its range of motion. The actuator must further be able to hold ergonomic support in the users selected position against the traction exerted on the Bowden cable wire by the pressure of the user sitting on it.
Prior art actuators achieve these design goals through mechanisms that were complex, and therefore expensive, See, for example, U.S. Pat. No. 5,794,479, U.S. Pat. No. 6,178,838, U.S. Pat. No. 6,230,867 B1. The use of such overrunning clutches, ratchets, bearings, and eccentric rings involve a large number of parts, increasing the expense of the actuator both in terms of the number of parts required and their assembly. Moreover, such devices do not wear well and tend to break or slip after a number of use cycles shorter than the predicted lifetime of the seat in which they are installed. There is a need in the industry for an ergonomic support actuator that reduces cost, decreases complexity, and increases durability.